Downhole production well control system and method

ABSTRACT

A downhole production well control system is provided for automatically controlling downhole tools in response to sensed selected downhole parameters. An important feature of this invention is that the automatic control is initiated downhole without an initial control signal from the surface or from some other external source. This control system generally comprises downhole sensors, downhole electromechanical devices and downhole computerized control electronics whereby the control electronics automatically control the electromechanical devices based on input from the downhole sensors. Thus, using the downhole sensors, the downhole computerized control system will monitor actual downhole parameters (such as pressure, temperature, flow, gas influx, etc.) and automatically execute control instructions when the monitored downhole parameters are outside a selected operating range (e.g., indicating an unsafe condition). The automatic control instructions will then cause an electromechanical control device (such as a valve) to actuate a suitable tool (for example, actuate a sliding sleeve or packer; or close a pump or other fluid flow device). The downhole control system of this invention also includes transceivers for two-way communication with the surface as well as a telemetry device for communicating from the surface of the production well to a remote location.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a method and apparatus for thecontrol of oil and gas production wells. More particularly, thisinvention relates to a method and apparatus for automaticallycontrolling petroleum production wells using downhole computerizedcontrol systems. This invention also relates to a control system forcontrolling production wells, including multiple zones within a singlewell, from a remote location.

2. The Prior Art

The control of oil and gas production wells constitutes an on-goingconcern of the petroleum industry due, in part, to the enormous monetaryexpense involved as well as the risks associated with environmental andsafety issues.

Production well control has become particularly important and morecomplex in view of the industry wide recognition that wells havingmultiple branches (i.e., multilateral wells) will be increasinglyimportant and commonplace. Such multilateral wells include discreteproduction zones which produce fluid in either common or discreteproduction tubing. In either case, there is a need for controlling zoneproduction, isolating specific zones and otherwise monitoring each zonein a particular well.

Before describing the current state-of-the-art relative to suchproduction well control systems and methods, a brief description will bemade of the production systems, per se, in need of control. One type ofproduction system utilizes electrical submersible pumps (ESP) forpumping fluids from downhole. In addition, there are two other generaltypes of productions systems for oil and gas wells, namely plunger liftand gas lift. Plunger lift production systems include the use of a smallcylindrical plunger which travels through tubing extending from alocation adjacent the producing formation down in the borehole tosurface equipment located at the open end of the borehole. In general,fluids which collect in the borehole and inhibit the flow of fluids outof the formation and into the wellbore, are collected in the tubing.Periodically, the end of the tubing is opened at the surface and theaccumulated reservoir pressure is sufficient to force the plunger up thetubing. The plunger carries with it to the surface a load of accumulatedfluids which are ejected out the top of the well thereby allowing gas toflow more freely from the formation into the wellbore and be deliveredto a distribution system at the surface. After the flow of gas has againbecome restricted due to the further accumulation of fluids downhole, avalve in the tubing at the surface of the well is closed so that theplunger then falls back down the tubing and is ready to lift anotherload of fluids to the surface upon the reopening of the valve.

A gas lift production system includes a valve system for controlling theinjection of pressurized gas from a source external to the well, such asanother gas well or a compressor, into the borehole. The increasedpressure from the injected gas forces accumulated formation fluids up acentral tubing extending along the borehole to remove the fluids andrestore the free flow of gas and/or oil from the formation into thewell. In wells where liquid fall back is a problem during gas lift,plunger lift may be combined with gas lift to improve efficiency.

In both plunger lift and gas lift production systems, there is arequirement for the periodic operation of a motor valve at the surfaceof the wellhead to control either the flow of fluids from the well orthe flow of injection gas into the well to assist in the production ofgas and liquids from the well. These motor valves are conventionallycontrolled by timing mechanisms and are programmed in accordance withprinciples of reservoir engineering which determine the length of timethat a well should be either "shut in" and restricted from the flowingof gas or liquids to the surface and the time the well should be"opened" to freely produce. Generally, the criteria used for operationof the motor valve is strictly one of the elapse of a preselected timeperiod. In most cases, measured well parameters, such as pressure,temperature, etc. are used only to override the timing cycle in specialconditions.

It will be appreciated that relatively simple, timed intermittentoperation of motor valves and the like is often not adequate to controleither outflow from the well or gas injection to the well so as tooptimize well production. As a consequence, sophisticated computerizedcontrollers have been positioned at the surface of production wells forcontrol of downhole devices such as the motor valves.

In addition, such computerized controllers have been used to controlother downhole devices such as hydro-mechanical safety valves. Thesetypically microprocessor based controllers are also used for zonecontrol within a well and, for example, can be used to actuate slidingsleeves or packers by the transmission of a surface command to downholemicroprocessor controllers and/or electromechanical control devices.

The surface controllers are often hardwired to downhole sensors whichtransmit information to the surface such as pressure, temperature andflow. This data is then processed at the surface by the computerizedcontrol system. Electrically submersible pumps use pressure andtemperature readings received at the surface from downhole sensors tochange the speed of the pump in the borehole. As an alternative todownhole sensors, wire line production logging tools are also used toprovide downhole data on pressure, temperature, flow, gamma ray andpulse neutron using a wire line surface unit. This data is then used forcontrol of the production well.

There are numerous prior art patents related to the control of oil andgas production wells. In general, these prior patents relate to (1)surface control systems using a surface microprocessor and (2) downholecontrol systems which are initiated by surface control signals.

The surface control system patents generally disclose computerizedsystems for monitoring and controlling a gas/oil production well wherebythe control electronics is located at the surface and communicates withsensors and electromechanical devices near the surface. An example of asystem of this type is described in U.S. Pat. No. 4,633,954 ('954) toDixon et al. The system described in the '954 patent includes a fullyprogrammable microprocessor controller which monitors downholeparameters such as pressure and flow and controls the operation of gasinjection to the well, outflow of fluids from the well or shutting in ofthe well to maximize output of the well. This particular system includesbattery powered solid state circuitry comprising a keyboard, aprogrammable memory, a microprocessor, control circuitry and a liquidcrystal display. Another example of a control system of this type isdescribed in U.S. Pat. No. 5,132,904 ('904) to Lamp. The '904 patentdiscloses a system similar to the '954 patent and in addition alsodescribes a feature wherein the controller includes serial and parallelcommunication ports through which all communications to and from thecontroller pass. Hand held devices or portable computers capable ofserial communication may access the controller. A telephone modem ortelemetry link to a central host computer may also be used to permitseveral controllers to be accessed remotely.

U.S. Pat. No. 4,757,314 ('314) to Aubin et al describes an apparatus forcontrolling and monitoring a well head submerged in water. This systemincludes a plurality of sensors, a plurality of electromechanical valvesand an electronic control system which communicates with the sensors andvalves. The electronic control system is positioned in a water tightenclosure and the water tight enclosure is submerged underwater. Theelectronics located in the submerged enclosure control and operate theelectromechanical valves based on input from the sensors. In particular,the electronics in the enclosure uses the decision making abilities ofthe microprocessor to monitor the cable integrity from the surface tothe well head to automatically open or close the valves should a breakin the line occur.

The downhole control system patents generally disclose downholemicroprocessor controllers, electromechanical control devices andsensors. Examples include U.S. Pat. No. 4,915,168 ('168) to Upchurch andU.S. Pat. No. 5,273,112 ('112) to Schultz. However, in each and everycase, the microprocessor controllers transmit control signals only uponactuation from a surface or other external control signal. There is noteaching in any of these patents that the downhole microprocessorcontrollers themselves may automatically initiate the control of theelectromechanical devices based on preprogrammed instructions.Similarly, none of the aforementioned patents directed to microprocessorbased control systems for controlling the production from oil and gaswells, including the aforementioned '954, '904 and '314 patents,disclose the use of downhole electronic controllers, electromechanicalcontrol devices and sensors whereby the electronic control units willautomatically control the electromechanical devices based on input fromthe sensor without the need for a surface or other external controlsignal.

It will be appreciated that the downhole control system of the typesdisclosed in the '168 and '112 patents are closely analogous to thesurface based control systems such as disclosed in the '954, '904 and'314 patents in that a surface controller is required at each well toinitiate and transmit the control instructions to the downholemicroprocessor. Thus, in all cases, some type of surface controller andassociated support platform at each well is needed.

While it is well recognized that petroleum production wells will haveincreased production efficiencies and lower operating costs if surfacecomputer based controllers and downhole microprocessor controller(actuated by external or surface signals) of the type discussedhereinabove are used, the presently implemented control systemsnevertheless suffer from drawbacks and disadvantages. For example, asmentioned, all of these prior art systems generally require a surfaceplatform at each well for supporting the control electronics andassociated equipment. However, in many instances, the well operatorwould rather forego building and maintaining the costly platform. Thus,a problem is encountered in that use of present surface controllersrequire the presence of a location for the control system, namely theplatform. Still another problem associated with known surface controlsystems such as the type disclosed in the '168 and '112 patents whereina downhole microprocessor is actuated by a surface signal is thereliability of surface to downhole signal integrity. It will beappreciated that should the surface signal be in any way compromised onits way downhole, then important control operations (such as preventingwater from flowing into the production tubing) will not take place asneeded.

In multilateral wells where multiple zones are controlled by a singlesurface control system, an inherent risk is that if the surface controlsystem fails or otherwise shuts down, then all of the downhole tools andother production equipment in each separate zone will similarly shutdown leading to a large loss in production and, of course, a loss inrevenue.

Still another significant drawback of present production well controlsystems involves the extremely high cost associated with implementingchanges in well control and related workover operations. Presently, if aproblem is detected at the well, the customer is required to send a rigto the wellsite at an extremely high cost (e.g., 5 million dollars for30 days of offshore work). The well must then be shut in during theworkover causing a large loss in revenues (e.g., 1.5 million dollars fora 30 day period). Associated with these high costs are the relativelyhigh risks of adverse environmental impact due to spills and otheraccidents as well as potential liability of personnel at the rig site.Of course, these risks can lead to even further costs. Because of thehigh costs and risks involved, in general, a customer may delayimportant and necessary workover of a single well until other wells inthat area encounter problems. This delay may cause the production of thewell to decrease or be shut in until the rig is brought in.

Still other problems associated with present production well controlsystems involve the need for wireline formation evaluation to sensechanges in the formation and fluid composition. Unfortunately, suchwireline formation evaluation is extremely expensive and time consuming.In addition, it requires shut-in of the well and does not provide "realtime" information. The need for real time information regarding theformation and fluid is especially acute in evaluating undesirable waterflow into the production fluids.

SUMMARY OF THE INVENTION

The above-discussed and other problems and deficiencies of the prior artare overcome or alleviated by the production well control system of thepresent invention. In accordance with a first embodiment of the presentinvention, a downhole production well control system is provided forautomatically controlling downhole tools in response to sensed selecteddownhole parameters. An important feature of this invention is that theautomatic control is initiated downhole without an initial controlsignal from the surface or from some other external source.

The first embodiment of the present invention generally comprisesdownhole sensors, downhole electromechanical devices and downholecomputerized control electronics whereby the control electronicsautomatically control the electromechanical devices based on input fromthe downhole sensors. Thus, using the downhole sensors, the downholecomputerized control system will monitor actual downhole parameters(such as pressure, temperature, flow, gas influx, etc.) andautomatically execute control instructions when the monitored downholeparameters are outside a selected operating range (e.g., indicating anunsafe condition). The automatic control instructions will then cause anelectromechanical control device (such as a valve) to actuate a suitabletool (for example, actuate a sliding sleeve or packer; or close a pumpor other fluid flow device).

The downhole control system of this invention also includes transceiversfor two-way communication with the surface as well as a telemetry devicefor communicating from the surface of the production well to a remotelocation.

The downhole control system is preferably located in each zone of a wellsuch that a plurality of wells associated with one or more platformswill have a plurality of downhole control systems, one for each zone ineach well. The downhole control systems have the ability to communicatewith other downhole control systems in other zones in the same ordifferent wells. In addition, as discussed in more detail with regard tothe second embodiment of this invention, each downhole control system ina zone may also communicate with a surface control system. The downholecontrol system of this invention thus is extremely well suited for usein connection with multilateral wells which include multiple zones.

The selected operating range for each tool controlled by the downholecontrol system of this invention is programmed in a downhole memoryeither before or after the control system is lowered downhole. Theaforementioned transceiver may be used to change the operating range oralter the programming of the control system from the surface of the wellor from a remote location.

A power source provides energy to the downhole control system. Power forthe power source can be generated in the borehole (e.g., by a turbinegenerator), at the surface or be supplied by energy storage devices suchas batteries (or a combination of one or more of these power sources).The power source provides electrical voltage and current to the downholeelectronics, electromechanical devices and sensors in the borehole.

In contrast to the aforementioned prior art well control systems whichconsist either of computer systems located wholly at the surface ordownhole computer systems which require an external (e.g., surface)initiation signal (as well as a surface control system), the downholewell production control system of this invention automatically operatesbased on downhole conditions sensed in real time without the need for asurface or other external signal. This important feature constitutes asignificant advance in the field of production well control. Forexample, use of the downhole control system of this invention obviatesthe need for a surface platform (although such surface platforms maystill be desirable in certain applications such as when a remotemonitoring and control facility is desired as discussed below inconnection with the second embodiment of this invention). The downholecontrol system of this invention is also inherently more reliable sinceno surface to downhole actuation signal is required and the associatedrisk that such an actuation signal will be compromised is thereforerendered moot. With regard to multilateral (i.e., multi-zone) wells,still another advantage of this invention is that, because the entireproduction well and its multiple zones are not controlled by a singlesurface controller, then the risk that an entire well including all ofits discrete production zones will be shut-in simultaneously is greatlyreduced.

In accordance with a second embodiment of the present invention, asystem adapted for controlling and/or monitoring a plurality ofproduction wells from a remote location is provided. This system iscapable of controlling and/or monitoring:

(1) a plurality of zones in a single production well;

(2) a plurality of zones/wells in a single location (e.g., a singleplatform); or

(3) a plurality of zones/wells located at a plurality of locations(e.g., multiple platforms).

The multizone and/or multiwell control system of this invention iscomposed of multiple downhole electronically controlledelectromechanical devices (sometimes referred to as downhole modules),and multiple computer based surface systems operated from multiplelocations. Important functions for these systems include the ability topredict the future flow profile of multiple wells and to monitor andcontrol the fluid or gas flow from either the formation into thewellbore, or from the wellbore to the surface. The control system of thesecond embodiment of this invention is also capable of receiving andtransmitting data from multiple remote locations such as inside theborehole, to or from other platforms, or from a location away from anywell site.

The downhole control devices interface to the surface system usingeither a wireless communication system or through an electrical hardwired connection. The downhole control systems in the wellbore cantransmit and receive data and/or commands to/from the surface system.The data transmission from inside the wellbore can be done by allowingthe surface system to poll each individual device in the hole, althoughindividual devices will be allowed to take control of the communicationsduring an emergency. The devices downhole may be programmed while in thewellbore by sending the proper command and data to adjust the parametersbeing monitored due to changes in borehole and flow conditions and/or tochange its primary function in the wellbore.

The surface system may control the activities of the downhole modules byrequesting data on a periodic basis, and commanding the modules to openor close the electromechanical control devices, and/or change monitoringparameters due to changes in long term borehole conditions. The surfacesystem at one location will be capable of interfacing with a system inanother location via phone lines, satellite communication or othercommunicating means. Preferably, a remote central control systemcontrols and/or monitors all of the zones, wells and/or platforms from asingle remote location.

In accordance with a third embodiment of the present invention, thedownhole control systems are associated with permanent downholeformation evaluation sensors which remain downhole throughout productionoperations. These formation evaluation sensors for formationmeasurements may include, for example, gamma ray detection for formationevaluation, neutron porosity, resistivity, acoustic sensors and pulseneutron which can, in real time, sense and evaluate formation parametersincluding important information regarding water migrating from differentzones. Significantly, this information can be obtained prior to thewater actually entering the producing tubing and therefore correctiveaction (i.e., closing of a valve or sliding sleeve) or formationtreatment can be taken prior to water being produced. This real timeacquisition of formation data in the production well constitutes animportant advance over current wireline techniques in that the presentinvention is far less costly and can anticipate and react to potentialproblems before they occur. In addition, the formation evaluationsensors themselves can be placed much closer to the actual formation(i.e., adjacent the casing or downhole completion tool) then wirelinedevices which are restricted to the interior of the production tubing.

The above-discussed and other features and advantages of the presentinvention will be appreciated by and understood by those skilled in theart from the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, wherein like elements are numbered alikein the several FIGURES:

FIG. 1 is a diagrammatic view depicting the multiwell/multizone controlsystem of the present invention for use in controlling a plurality ofoffshore well platforms;

FIG. 2 is an enlarged diagrammatic view of a portion of FIG. 1 depictinga selected well and selected zones in such selected well and a downholecontrol system for use therewith;

FIG. 3 is an enlarged diagrammatic view of a portion of FIG. 2 depictingcontrol systems for both open hole and cased hole completion zones;

FIG. 4 is a block diagram depicting the multiwell/multizone controlsystem in accordance with the present invention;

FIG. 5 is a block diagram depicting a surface control system for usewith the multiwell/multizone control system of the present invention;

FIG. 5A is a block diagram of a communications system using senseddownhole pressure conditions;

FIG. 5B is a block diagram of a portion of the communications system ofFIG. 5A;

FIG. 5C is a block diagram of the data acquisition system used in thesurface control system of FIG. 5;

FIG. 6 is a block diagram depicting a downhole production well controlsystem in accordance with the present invention;

FIG. 7 is an electrical schematic of the downhole production wellcontrol system of FIG. 6;

FIG. 8 is a cross-sectional elevation view of a retrievable pressuregauge side pocket mandrel in accordance with the present invention;

FIG. 8A is an enlarged view of a portion of FIG. 8;

FIG. 9 is a diagrammatic view of a subsurface safety valve position andpressure monitoring system;

FIG. 10 is a diagrammatic view of a remotely controlledinflation/deflation device for downhole pressure monitoring;

FIGS. 11A and 11B are diagrammatic views of a system for remotelyactuated downhole tool stops in respective extended and retractedpositions;

FIG. 12 is a diagrammatic view of a remotely controlled fluid/gascontrol system;

FIG. 13 is a diagrammatic view of a remotely controlled shut off valveand variable choke assembly; and

FIG. 14 is a cross-sectional side elevation view of a downhole formationevaluation sensor in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

This invention relates to a system for controlling production wells froma remote location. In particular, in an embodiment of the presentinvention, a control and monitoring system is described for controllingand/or monitoring at least two zones in a single well from a remotelocation. The present invention also includes the remote control and/ormonitoring of multiple wells at a single platform (or other location)and/or multiple wells located at multiple platforms or locations. Thus,the control system of the present invention has the ability to controlindividual zones in multiple wells on multiple platforms, all from aremote location. The control and/or monitoring system of this inventionis comprised of a plurality of surface control systems or moduleslocated at each well head and one or more downhole control systems ormodules positioned within zones located in each well. These subsystemsallow monitoring and control from a single remote location of activitiesin different zones in a number of wells in near real time.

As will be discussed in some detail hereinafter in connection with FIGS.2, 6 and 7, in accordance with a preferred embodiment of the presentinvention, the downhole control system is composed of downhole sensors,downhole control electronics and downhole electromechanical modules thatcan be placed in different locations (e.g., zones) in a well, with eachdownhole control system having a unique electronics address. A number ofwells can be outfitted with these downhole control devices. The surfacecontrol and monitoring system interfaces with all of the wells where thedownhole control devices are located to poll each device for datarelated to the status of the downhole sensors attached to the modulebeing polled. In general, the surface system allows the operator tocontrol the position, status, and/or fluid flow in each zone of the wellby sending a command to the device being controlled in the wellbore.

As will be discussed hereinafter, the downhole control modules for usein the multizone or multiwell control system of this invention mayeither be controlled using an external or surface command as is known inthe art or the downhole control system may be actuated automatically inaccordance with a novel control system which controls the activities inthe wellbore by monitoring the well sensors connected to the dataacquisition electronics. In the latter case, a downhole computer (e.g.,microprocessor) will command a downhole tool such as a packer, slidingsleeve or valve to open, close, change state or do whatever other actionis required if certain sensed parameters are outside the normal orpreselected well zone operating range. This operating range may beprogrammed into the system either prior to being placed in the boreholeor such programming may be effected by a command from the surface afterthe downhole control module has been positioned downhole in thewellbore.

Referring now to FIGS. 1 and 4, the multiwell/multizone monitoring andcontrol system of the present invention may include a remote centralcontrol center 10 which communicates either wirelessly or via telephonewires to a plurality of well platforms 12. It will be appreciated thatany number of well platforms may be encompassed by the control system ofthe present invention with three platforms namely, platform 1, platform2, and platform N being shown in FIGS. 1 and 4. Each well platform hasassociated therewith a plurality of wells 14 which extend from eachplatform 12 through water 16 to the surface of the ocean floor 18 andthen downwardly into formations under the ocean floor. It will beappreciated that while offshore platforms 12 have been shown in FIG. 1,the group of wells 14 associated with each platform are analogous togroups of wells positioned together in an area of land; and the presentinvention therefore is also well suited for control of land based wells.

As mentioned, each platform 12 is associated with a plurality of wells14. For purposes of illustration, three wells are depicted as beingassociated with platform number 1 with each well being identified aswell number 1, well number 2 and well number N. As is known, a givenwell may be divided into a plurality of separate zones which arerequired to isolate specific areas of a well for purposes of producingselected fluids, preventing blowouts and preventing water intake. Suchzones may be positioned in a single vertical well such as well 19associated with platform 2 shown in FIG. 1 or such zones can result whenmultiple wells are linked or otherwise joined together. A particularlysignificant contemporary feature of well production is the drilling andcompletion of lateral or branch wells which extend from a particularprimary wellbore. These lateral or branch wells can be completed suchthat each lateral well constitutes a separable zone and can be isolatedfor selected production. A more complete description of wellborescontaining one or more laterals (known as multilaterals) can be found inU.S. Pat. Nos. 4,807,407, 5,325,924 and U.S. application Ser. No.08/187,277 (now U.S. Pat. No. 5,411,082), all of the contents of each ofthose patents and applications being incorporated herein by reference.

With reference to FIGS. 1-4, each of the wells 1, 2 and 3 associatedwith platform 1 include a plurality of zones which need to be monitoredand/or controlled for efficient production and management of the wellfluids. For example, with reference to FIG. 2, well number 2 includesthree zones, namely zone number 1, zone number 2 and zone number N. Eachof zones 1, 2 and N have been completed in a known manner; and moreparticularly have been completed in the manner disclosed inaforementioned application Ser. No. 08/187,277. Zone number 1 has beencompleted using a known slotted liner completion, zone number 2 has beencompleted using an open hole selective completion and zone number N hasbeen completed using a cased hole selective completion with slidingsleeves. Associated with each of zones 1, 2 and N is a downhole controlsystem 22. Similarly, associated with each well platform 1, 2 and N is asurface control system 24.

As discussed, the multiwell/multizone control system of the presentinvention is comprised of multiple downhole electronically controlledelectromechanical devices and multiple computer based surface systemsoperated form multiple locations. An important function of these systemsis to predict the future flow profile of multiple wells and monitor andcontrol the fluid or gas flow from the formation into the wellbore andfrom the wellbore into the surface. The system is also capable ofreceiving and transmitting data from multiple locations such as insidethe borehole, and to or from other platforms 1, 2 or N or from alocation away from any well site such as central control center 10.

The downhole control systems 22 will interface to the surface system 24using a wireless communication system or through an electrical wire(i.e., hardwired) connection. The downhole systems in the wellbore cantransmit and receive data and/or commands to or from the surface and/orto or from other devices in the borehole. Referring now to FIG. 5, thesurface system 24 is composed of a computer system 30 used forprocessing, storing and displaying the information acquired downhole andinterfacing with the operator. Computer system 30 may be comprised of apersonal computer or a work station with a processor board, short termand long term storage media, video and sound capabilities as is wellknown. Computer control 30 is powered by power source 32 for providingenergy necessary to operate the surface system 24 as well as anydownhole system 22 if the interface is accomplished using a wire orcable. Power will be regulated and converted to the appropriate valuesrequired to operate any surface sensors (as well as a downhole system ifa wire connection between surface and downhole is available).

A surface to borehole transceiver 34 is used for sending data downholeand for receiving the information transmitted from inside the wellboreto the surface. The transceiver converts the pulses received fromdownhole into signals compatible with the surface computer system andconverts signals from the computer 30 to an appropriate communicationsmeans for communicating downhole to downhole control system 22.Communications downhole may be effected by a variety of known methodsincluding hardwiring and wireless communications techniques. A preferredtechnique transmits acoustic signals down a tubing string such asproduction tubing string 38 (see FIG. 2) or coiled tubing. Acousticalcommunication may include variations of signal frequencies, specificfrequencies, or codes or acoustical signals or combinations of these.The acoustical transmission media may include the tubing string asillustrated in U.S. Pat. Nos. 4,375,239; 4,347,900 or 4,378,850, all ofwhich are incorporated herein by reference. Alternatively, theacoustical transmission may be transmitted through the casing stream,electrical line, slick line, subterranean soil around the well, tubingfluid or annulus fluid. A preferred acoustic transmitter is described inU.S. Pat. No. 5,222,049, all of the contents of which is incorporatedherein by reference thereto, which discloses a ceramic piezoelectricbased transceiver. The piezoelectric wafers that compose the transducerare stacked and compressed for proper coupling to the medium used tocarry the data information to the sensors in the borehole. Thistransducer will generate a mechanical force when alternating currentvoltage is applied to the two power inputs of the transducer. The signalgenerated by stressing the piezoelectric wafers will travel along theaxis of the borehole to the receivers located in the tool assembly wherethe signal is detected and processed. The transmission medium where theacoustic signal will travel in the borehole can be production tubing orcoil tubing.

Communications can also be effected by sensed downhole pressureconditions which may be natural conditions or which may be a codedpressure pulse or the like introduced into the well at the surface bythe operator of the well. Suitable systems describing in more detail thenature of such coded pressure pulses are described in U.S. Pat. Nos.4,712,613 to Nieuwstad, U.S. Pat. No. 4,468,665 to Thawley, U.S. Pat.No. 3,233,674 to Leutwyler and U.S. Pat. No. 4,078,620 to Westlake; U.S.Pat. No. 5,226,494 to Rubbo et al and U.S. Pat. No. 5,343,963 to Bouldinet al. Similarly, the aforementioned '168 patent to Upchurch and '112patent to Schultz also disclose the use of coded pressure pulses incommunicating from the surface downhole.

A preferred system for sensing downhole pressure conditions is depictedin FIGS. 5A and 5B. Referring to FIG. 5A, this system includes ahandheld terminal 300 used for programming the tool at the surface,batteries (not shown) for powering the electronics and actuationdownhole, a microprocessor 302 used for interfacing with the handheldterminal and for setting the frequencies to be used by the ErasableProgrammable Logic Device (EPLD) 304 for activation of the drivers,preamplifiers 306 used for conditioning the pulses from the surface,counters (EPLD) 304 used for the acquisition of the pulses transmittedfrom the surface for determination of the pulse frequencies, and toenable the actuators 306 in the tool; and actuators 308 used for thecontrol and operation of electromechanical devices and/or ignitors.

Referring to FIG. 5B, the EPLD system 304 is preferably comprised of sixcounters: A four bit counter for surface pulse count and for control ofthe actuation of the electromechanical devices. A 10 bit counter toreduce the frequency of Clock in from 32.768 KHz to 32 Hz; and a 10 bitcounter to count the deadtime frequency. Two counters are used todetermine the proper frequency of pulses. Only one frequency counter isenabled at any time. A shift register is set by the processor to retainthe frequency settings. The 10 bit devices also enable the pulse counterto increment the count if a pulse is received after the deadtime elapse,and before the pulse window count of six seconds expire. The system willbe reset if pulse is not received during the six seconds valid period.An AND gate is located between the input pulses and the clock in thepulse counter. The AND gate will allow the pulse from a strain gauge toreach the counter if the enable line from the 10 bit counter is low. Atwo input OR gate will reset the pulse counter from the 10 bit counteror the master reset from the processor. A three input OR gate will beused for resetting the 11, 10 bit counters, as well as the frequencycounters.

The communications system of of FIGS. 5A and 5B may operate as follows:

1. Set the tool address (frequencies) using the handheld terminal at thesurface;

2. Use the handheld terminal to also set the time delay for the tool toturn itself on and listen to the pulses transmitted from the surface;

3. The processor 302 will set the shift register with a binary numberwhich will indicate to the counters the frequencies (address) it shouldacknowledge for operation of the actuators;

4. The operator will use an appropriate transmitter at the surfacesystem 24 to generate the proper frequencies to be sent to the tooldownhole;

5. The downhole electronics 22 will receive the pulses from the surface,determine if they are valid, and turn on or off the actuators;

6. In one preferred embodiment described in steps 6-8, there are a totalof sixteen different frequencies that can be used to activate thesystems downhole. Each downhole system will require two frequencies tobe sent from the surface for proper activation.

7. The surface system 24 will interface to the tools' processor 302 toset the two frequencies for communication and activation of the systemsin the borehole. Each frequency spaced at multiples of 30 secondsintervals is composed of four pulses. A system downhole will beactivated when 8 pulses at the two preset frequencies are received bythe electronics in the tool. There has to be 4 pulses at one frequencyfollowed by 4 pulses at a second frequency.

5. A counter will monitor the frequencies downhole and will reset thehardware if a pulse is not received within a 6 second window.

Also, other suitable communications techniques include radiotransmission from the surface location or from a subsurface location,with corresponding radio feedback from the downhole tools to the surfacelocation or subsurface location; the use of microwave transmission andreception; the use of fiber optic communications through a fiber opticcable suspended from the surface to the downhole control package; theuse of electrical signaling from a wire line suspended transmitter tothe downhole control package with subsequent feedback from the controlpackage to the wire line suspended transmitter/receiver. Communicationmay also consist of frequencies, amplitudes, codes or variations orcombinations of these parameters or a transformer coupled techniquewhich involves wire line conveyance of a partial transformer to adownhole tool. Either the primary or secondary of the transformer isconveyed on a wire line with the other half of the transformer residingwithin the downhole tool. When the two portions of the transformer aremated, data can be interchanged.

Referring again to FIG. 5, the control surface system 24 furtherincludes a printer/plotter 40 which is used to create a paper record ofthe events occurring in the well. The hard copy generated by computer 30can be used to compare the status of different wells, compare previousevents to events occurring in existing wells and to get formationevaluation logs. Also communicating with computer control 30 is a dataacquisition system 42 which is used for interfacing the well transceiver34 to the computer 30 for processing. The data acquisition system 42 iscomprised of analog and digital inputs and outputs, computer businterfaces, high voltage interfaces and signal processing electronics.An embodiment of data acquisition sensor 42 is shown in FIG. 5C andincludes a pre-amplifier 320, band pass filter 322, gain controlledamplifier 324 and analog to digital converter 326. The data acquisitionsystem (ADC) will process the analog signals detected by the surfacereceiver to conform to the required input specifications to themicroprocessor based data processing and control system. The surfacereceiver 34 is used to detect the pulses received at the surface frominside the wellbore and convert them into signals compatible with thedata acquisition preamplifier 320. The signals from the transducer willbe low level analog voltages. The preamplifier 320 is used to increasethe voltage levels and to decrease the noise levels encountered in theoriginal signals from the transducers. Preamplifier 320 will also bufferthe data to prevent any changes in impedance or problems with thetransducer from damaging the electronics. The bandpass filter 322eliminates the high and low frequency noises that are generated fromexternal sources. The filter will allow the signals associated with thetransducer frequencies to pass without any significant distortion orattenuation. The gain controlled amplifier 324 monitors the voltagelevel on the input signal and amplifies or attenuates it to assure thatit stays within the acquired voltage ranges. The signals are conditionedto have the highest possible range to provide the largest resolutionthat can be achieved within the system. Finally, the analog to digitalconverter 326 will transform the analog signal received from theamplifier into a digital value equivalent to the voltage level of theanalog signal. The conversion from analog to digital will occur afterthe microprocessor 30 commands the tool to start a conversion. Theprocessor system 30 will set the ADC to process the analog signal into 8or 16 bits of information, The ADC will inform the processor when aconversion is taking place and when it is competed. The processor 30 canat any time request the ADC to transfer the acquired data to theprocessor.

Still referring to FIG. 5, the electrical pulses from the transceiver 34will be conditioned to fit within a range where the data can bedigitized for processing by computer control 30. Communicating with bothcomputer control 30 and transceiver 34 is a previously mentioned modem36. Modem 36 is available to surface system 24 for transmission of thedata from the well site to a remote location such as remote location 10or a different control surface system 24 located on, for example,platform 2 or platform N. At this remote location, the data can beviewed and evaluated, or again, simply be communicated to othercomputers controlling other platforms. The remote computer 10 can takecontrol over system 24 interfacing with the downhole control modules 22and acquired data from the wellbore and/or control the status of thedownhole devices and/or control the fluid flow from the well or from theformation. Also associated with the control surface system 24 is a depthmeasurement system which interfaces with computer control system 30 forproviding information related to the location of the tools in theborehole as the tool string is lowered into the ground. Finally, controlsurface system 24 also includes one or more surface sensors 46 which areinstalled at the surface for monitoring well parameters such aspressure, rig pumps and heave, all of which can be connected to thesurface system to provide the operator with additional information onthe status of the well.

Surface system 24 can control the activities of the downhole controlmodules 22 by requesting data on a periodic basis and commanding thedownhole modules to open, or close electromechanical devices and tochange monitoring parameters due to changes in long term boreholeconditions. As shown diagrammatically in FIG. 1, surface system 24, atone location such as platform 1, can interface with a surface system 24at a different location such as platforms 2 or N or the central remotecontrol sensor 10 via phone lines or via wireless transmission. Forexample, in FIG. 1, each surface system 24 is associated with an antenna48 for direct communication with each other (i.e., from platform 2 toplatform N), for direct communication with an antenna 50 located atcentral control system 10 (i.e., from platform 2 to control system 10)or for indirect communication via a satellite 52. Thus, each surfacecontrol center 24 includes the following functions:

1. Polls the downhole sensors for data information;

2. Processes the acquired information from the wellbore to provide theoperator with formation, tools and flow status;

3. Interfaces with other surface systems for transfer of data andcommands; and

4. Provides the interface between the operator and the downhole toolsand sensors.

In a less preferred embodiment of the present invention, the downholecontrol system 22 may be comprised of any number of known downholecontrol systems which require a signal from the surface for actuation.Examples of such downhole control systems include those described inU.S. Pat. Nos. 3,227,228; 4,796,669; 4,896,722; 4,915,168; 5,050,675;4,856,595; 4,971,160; 5,273,112; 5,273,113; 5,332,035; 5,293,937;5,226,494 and 5,343,963, all of the contents of each patent beingincorporated herein by reference thereto. All of these patents disclosevarious apparatus and methods wherein a microprocessor based controllerdownhole is actuated by a surface or other external signal such that themicroprocessor executes a control signal which is transmitted to anelectromechanical control device which then actuates a downhole toolsuch as a sliding sleeve, packer or valve. In this case, the surfacecontrol system 24 transmits the actuation signal to downhole controller22.

Thus, in accordance with an embodiment of this invention, theaforementioned remote central control center 10, surface control centers24 and downhole control systems 22 all cooperate to provide one or moreof the following functions:

1. Provide one or two-way communication between the surface system 24and a downhole tool via downhole control system 22;

2. Acquire, process, display and/or store at the surface datatransmitted from downhole relating to the wellbore fluids, gases andtool status parameters acquired by sensors in the wellbore;

3. Provide an operator with the ability to control tools downhole bysending a specific address and command information from the centralcontrol center 10 or from an individual surface control center 24 downinto the wellbore;

4. Control multiple tools in multiple zones within any single well by asingle remote surface system 24 or the remote central control center 10;

5. Monitor and/or control multiple wells with a single surface system 10or 24;

6. Monitor multiple platforms from a single or multiple surface systemworking together through a remote communications link or workingindividually;

7. Acquire, process and transmit to the surface from inside the wellboremultiple parameters related to the well status, fluid condition andflow, tool state and geological evaluation;

8. Monitor the well gas and fluid parameters and perform functionsautomatically such as interrupting the fluid flow to the surface,opening or closing of valves when certain acquired downhole parameterssuch as pressure, flow, temperature or fluid content are determined tobe outside the normal ranges stored in the systems' memory (as describedbelow with respect to FIGS. 6 and 7); and

9. Provide operator to system and system to operator interface at thesurface using a computer control surface control system.

10. Provide data and control information among systems in the wellbore.

In a preferred embodiment and in accordance with an important feature ofthe present invention, rather than using a downhole control system ofthe type described in the aforementioned patents wherein the downholeactivities are only actuated by surface commands, the present inventionutilizes a downhole control system which automatically controls downholetools in response to sensed selected downhole parameters without theneed for an initial control signal from the surface or from some otherexternal source. Referring to FIGS. 2, 3, 6 and 7, this downholecomputer based control system includes a microprocessor based dataprocessing and control system 50.

Electronics control system 50 acquires and processes data sent from thesurface as received from transceiver system 52 and also transmitsdownhole sensor information as received from the data acquisition system54 to the surface. Data acquisition system 54 will preprocess the analogand digital sensor data by sampling the data periodically and formattingit for transfer to processor 50. Included among this data is data fromflow sensors 56, formation evaluation sensors 58 and electromechanicalposition sensor 59 (these latter sensors 59 provide information onposition, orientation and the like of downhole tools). The formationevaluation data is processed for the determination of reservoirparameters related to the well production zone being monitored by thedownhole control module. The flow sensor data is processed and evaluatedagainst parameters stored in the downhole module's memory to determineif a condition exists which requires the intervention of the processorelectronics 50 to automatically control the electromechanical devices.It will be appreciated that in accordance with an important feature ofthis invention, the automatic control executed by processor 50 isinitiated without the need for an initiation or control signal from thesurface or from some other external source. Instead, the processor 50simply evaluates parameters existing in real time in the borehole assensed by flow sensors 56 and/or formation evaluations sensors 58 andthen automatically executes instructions for appropriate control. Notethat while such automatic initiation is an important feature of thisinvention, in certain situations, an operator from the surface may alsosend control instructions downwardly from the surface to the transceiversystem 52 and into the processor 50 for executing control of downholetools and other electronic equipment. As a result of this control, thecontrol system 50 may initiate or stop the fluid/gas flow from thegeological formation into the borehole or from the borehole to thesurface.

The downhole sensors associated with flow sensors 56 and formationevaluations sensors 58 may include, but are not limited to, sensors forsensing pressure, flow, temperature, oil/water content, geologicalformation, gamma ray detectors and formation evaluation sensors whichutilize acoustic, nuclear, resistivity and electromagnetic technology.It will be appreciated that typically, the pressure, flow, temperatureand fluid/gas content sensors will be used for monitoring the productionof hydrocarbons while the formation evaluation sensors will measure,among other things, the movement of hydrocarbons and water in theformation. The downhole computer (processor 50) may automaticallyexecute instructions for actuating electromechanical drivers 60 or otherelectronic control apparatus 62. In turn, the electromechanical driver60 will actuate an electromechanical device for controlling a downholetool such as a sliding sleeve, shut off device, valve, variable choke,penetrator, perf valve or gas lift tool. As mentioned, downhole computer50 may also control other electronic control apparatus such as apparatusthat may effect flow characteristics of the fluids in the well.

In addition, downhole computer 50 is capable of recording downhole dataacquired by flow sensors 56, formation evaluation sensors 58 andelectromechanical position sensors 59. This downhole data is recorded inrecorder 66. Information stored in recorder 66 may either be retrievedfrom the surface at some later date when the control system is broughtto the surface or data in the recorder may be sent to the transceiversystem 52 and then communicated to the surface.

The borehole transmitter/receiver 52 transfers data from downhole to thesurface and receives commands and data from the surface and betweenother downhole modules. Transceiver assembly 52 may consist of any knownand suitable transceiver mechanism and preferably includes a device thatcan be used to transmit as well as to receive the data in a half duplexcommunication mode, such as an acoustic piezoelectric device (i.e.,disclosed in aforementioned U.S. Pat. No. 5,222,049), or individualreceivers such as accelerometers for full duplex communications wheredata can be transmitted and received by the downhole toolssimultaneously. Electronics drivers may be used to control the electricpower delivered to the transceiver during data transmission.

It will be appreciated that the downhole control system 22 requires apower source 66 for operation of the system. Power source 66 can begenerated in the borehole, at the surface or it can be supplied byenergy storage devices such as batteries. Power is used to provideelectrical voltage and current to the electronics and electromechanicaldevices connected to a particular sensor in the borehole. Power for thepower source may come from the surface through hardwiring or may beprovided in the borehole such as by using a turbine. Other power sourcesinclude chemical reactions, flow control, thermal, conventionalbatteries, borehole electrical potential differential, solids productionor hydraulic power methods.

Referring to FIG. 7, an electrical schematic of downhole controller 22is shown. As discussed in detail above, the downhole electronics systemwill control the electromechanical systems, monitor formation and flowparameters, process data acquired in the borehole, and transmit andreceive commands and data to and from other modules and the surfacesystems. The electronics controller is composed of a microprocessor 70,an analog to digital converter 72, analog conditioning hardware 74,digital signal processor 76, communications interface 78, serial businterface 80, non-volatile solid state memory 82 and electromechanicaldrivers 60.

The microprocessor 70 provides the control and processing capabilitiesof the system. The processor will control the data acquisition, the dataprocessing, and the evaluation of the data for determination if it iswithin the proper operating ranges. The controller will also prepare thedata for transmission to the surface, and drive the transmitter to sendthe information to the surface. The processor also has theresponsibility of controlling the electromechanical devices 64.

The analog to digital converter 72 transforms the data from theconditioner circuitry into a binary number. That binary number relatesto an electrical current or voltage value used to designate a physicalparameter acquired from the geological formation, the fluid flow, orstatus of the electromechanical devices. The analog conditioninghardware processes the signals from the sensors into voltage values thatare at the range required by the analog to digital converter.

The digital signal processor 76 provides the capability of exchangingdata with the processor to support the evaluation of the acquireddownhole information, as well as to encode/decode data for transmitter52. The processor 70 also provides the control and timing for thedrivers 78.

The communication drivers 70 are electronic switches used to control theflow of electrical power to the transmitter. The processor 70 providesthe control and timing for the drivers 78.

The serial bus interface 80 allows the processor 70 to interact with thesurface data acquisition and control system 42 (see FIGS. 5 and 5C). Theserial bus 80 allows the surface system 74 to transfer codes and setparameters to the micro controller 70 to execute its functions downhole.

The electromechanical drivers 60 control the flow of electrical power tothe electromechanical devices 64 used for operation of the slidingsleeves, packers, safety valves, plugs and any other fluid controldevice downhole. The drivers are operated by the microprocessor 70.

The non-volatile memory 82 stores the code commands used by the microcontroller 70 to perform its functions downhole. The memory 82 alsoholds the variables used by the processor 70 to determine if theacquired parameters are in the proper operating range.

It will be appreciated that downhole valves are used for opening andclosing of devices used in the control of fluid flow in the wellbore.Such electromechanical downhole valve devices will be actuated bydownhole computer 50 either in the event that a borehole sensor value isdetermined to be outside a safe to operate range set by the operator orif a command is sent from the surface. As has been discussed, it is aparticularly significant feature of this invention that the downholecontrol system 22 permits automatic control of downhole tools and otherdownhole electronic control apparatus without requiring an initiation oractuation signal from the surface or from some other external source.This is in distinct contrast to prior art control systems whereincontrol is either actuated from the surface or is actuated by a downholecontrol device which requires an actuation signal from the surface asdiscussed above. It will be appreciated that the novel downhole controlsystem of this invention whereby the control of electromechanicaldevices and/or electronic control apparatus is accomplishedautomatically without the requirement for a surface or other externalactuation signal can be used separately from the remote well productioncontrol scheme shown in FIG. 1.

Turning now to FIGS. 2 and 3, an example of the downhole control system22 is shown in an enlarged view of well number 2 from platform 1depicting zones 1, 2 and N. Each of zones 1, 2 and N is associated witha downhole control system 22 of the type shown in FIGS. 6 and 7. In zone1, a slotted liner completion is shown at 69 associated with a packer71. In zone 2, an open hole completion is shown with a series of packers71 and intermittent sliding sleeves 75. In zone N, a cased holecompletion is shown again with the series of packers 77, sliding sleeve79 and perforating tools 81. The control system 22 in zone 1 includeselectromechanical drivers and electromechanical devices which controlthe packers 69 and valving associated with the slotted liner so as tocontrol fluid flow. Similarly, control system 22 in zone 2 includeelectromechanical drivers and electromechanical devices which controlthe packers, sliding sleeves and valves associated with that open holecompletion system. The control system 22 in zone N also includeselectromechanical drivers and electromechanical control devices forcontrolling the packers, sliding sleeves and perforating equipmentdepicted therein. Any known electromechanical driver 60 orelectromechanical control device 64 may be used in connection with thisinvention to control a downhole tool or valve. Examples of suitablecontrol apparatus are shown, for example, in commonly assigned U.S. Pat.Nos. 5,343,963; 5,199,497; 5,346,014; and 5,188,183, all of the contentsof which are incorporated herein by reference; FIGS. 2, 10 and 11 of the'168 patent to Upchurch and FIGS. 10 and 11 of the '160 patent toUpchurch; FIGS. 11-14 of the '112 patent to Schultz; and FIGS. 1-4 ofU.S. Pat. No. 3,227,228 to Bannister.

Controllers 22 in each of zones 1, 2 and N have the ability not only tocontrol the electromechanical devices associated with each of thedownhole tools. but also have the ability to control other electroniccontrol apparatus which may be associated with, for example, valving foradditional fluid control. The downhole control systems 22 in zones 1, 2and N further have the ability to communicate with each other (forexample through hard wiring) so that actions in one zone may be used toeffect the actions in another zone. This zone to zone communicationconstitutes still another important feature of the present invention. Inaddition, not only can the downhole computers 50 in each of controlsystems 22 communicate with each other, but the computers 50 also haveability (via transceiver system 52) to communicate through the surfacecontrol system 24 and thereby communicate with other surface controlsystems 24 at other well platforms (i.e., platforms 2 or N), at a remotecentral control position such as shown at 10 in FIG. 1, or each of theprocessors 50 in each downhole control system 22 in each zone 1, 2 or Ncan have the ability to communicate through its transceiver system 52 toother downhole computers 50 in other wells. For example, the downholecomputer system 22 in zone 1 of well 2 in platform 1 may communicatewith a downhole control system on platform 2 located in one of the zonesor one of the wells associated therewith. Thus, the downhole controlsystem of the present invention permits communication between computersin different wellbores, communication between computers in differentzones and communication between computers from one specific zone to acentral remote location.

Information sent from the surface to transceiver 52 may consist ofactual control information, or may consist of data which is used toreprogram the memory in processor 50 for initiating of automatic controlbased on sensor information. In addition to reprogramming information,the information sent from the surface may also be used to recalibrate aparticular sensor. Processor 50 in turn may not only send raw data andstatus information to the surface through transceiver 52, but may alsoprocess data downhole using appropriate algorithms and other methods sothat the information sent to the surface constitutes derived data in aform well suited for analysis.

Referring to FIG. 3, an enlarged view of zones 2 and N from well 2 ofplatform 1 is shown. As discussed, a plurality of downhole flow sensors56 and downhole formation evaluation sensors 58 communicate withdownhole controller 22. The sensors are permanently located downhole andare positioned in the completion string and/or in the borehole casing.It will be appreciated by those of ordinary skill in the art from areview of FIGS. 1-3 and the foregoing description, that as inpermanently deployed sensors 56 and 58, control system 22(incorporating, for example, a downhole computer and a downhole controldevice) is similarly permanently deployed downhole. That is, controlsystem 22 as depicted herein is an integral part of a permanent wellcompletion for the production of fluids. This permanent well completionis in contrast to the temporary control systems used in drill stemtesting (e.g., shut-in) devices (e.g., U.S. Pat. Nos. 4,915,168 and5,273,112) described in the background section hereinabove. Inaccordance with still another important feature of this invention,formation evaluation sensors may be incorporated in the completionstring such as shown at 58A-C in zone 2; or may be positioned adjacentthe borehole casing 78 such as shown at 58D-F in zone N. In the lattercase, the formation evaluation sensors are hardwired back to controlsystem 22. The formation evaluation sensors may be of the type describedabove including density, porosity and resistivity types. These sensorsmeasure formation geology, formation saturation, formation porosity, gasinflux, water content, petroleum content and formation chemical elementssuch as potassium, uranium and thorium. Examples of suitable sensors aredescribed in commonly assigned U.S. Pat. No. 5,278,758 (porosity), U.S.Pat. No. 5,134,285 (density) and U.S. Pat. No. 5,001,675(electromagnetic resistivity), all of the contents of each patent beingincorporated herein by reference.

Referring to FIG. 14, an example of a downhole formation evaluationsensor for permanent placement in a production well is shown at 280.This sensor 280 is comprised of a side pocket mandrel 282 which includesa primary longitudinal bore 284 and a laterally displaced side pocket286. Mandrel 282 includes threading 288 at both ends for attachment toproduction tubing. Positioned sequentially in spaced relationlongitudinally along side pocket 286 are a plurality (in this case 3) ofacoustic, electromagnetic or nuclear receivers 290 which are sandwichedbetween a pair of respective acoustic, electromagnetic or nucleartransmitters 292. Transmitters 292 and receivers 290 all communicatewith appropriate and known electronics for carrying out formationevaluation measurements.

The information regarding the formation which is obtained bytransmitters 292 and receivers 286 will be forwarded to a downholemodule 22 and transmitted to the surface using any of the aforementionedhardwired or wireless communications techniques. In the embodiment shownin FIG. 14, the formation evaluation information is transmitted to thesurface on inductive coupler 294 and tubular encased conductor (TEC)296, both of which will be described in detail hereinafter.

As mentioned above, in the prior art, formation evaluation in productionwells was accomplished using expensive and time consuming wire linedevices which was positioned through the production tubing. The onlysensors permanently positioned in a production well were those used tomeasure temperature, pressure and fluid flow. In contrast, the presentinvention permanently locates formation evaluation sensors downhole inthe production well. The permanently positioned formation evaluationsensors of the present invention will monitor both fluid flow and, moreimportantly, will measure formation parameters so that changingconditions in the formation will be sensed before problems occur. Forexample, water in the formation can be measured prior to such waterreaching the borehole and therefore water will be prevented from beingproduced in the borehole. At present, water is sensed only after itenters the production tubing.

The formation evaluation sensors of this invention are located closer tothe formation as compared to wireline sensors in the production tubingand will therefore provide more accurate results. Since the formationevaluation data will constantly be available in real or near real time,there will be no need to periodically shut in the well and performcostly wireline evaluations.

The multiwell/multizone production well control system of the presentinvention may be operated as follows:

1. Place the downhole systems 22 in the tubing string 38.

2. Use the surface computer system 24 to test the downhole modules 22going into the borehole to assure that they are working properly.

3. Program the modules 22 for the proper downhole parameters to bemonitored.

4. Install and interface the surface sensors 46 to the computercontrolled system 24.

5. Place the downhole modules 22 in the borehole, and assure that theyreach the proper zones to be monitored and/or controlled by gatheringthe formation natural gamma rays in the borehole, and comparing the datato existing MWD or wireline logs, and monitoring the informationprovided by the depth measurement module 44.

6. Collect data at fixed intervals after all downhole modules 22 havebeen installed by polling each of the downhole systems 22 in theborehole using the surface computer based system 24.

7. If the electromechanical devices 64 need to be actuated to controlthe formation and/or well flow, the operator may send a command to thedownhole electronics module 50 instructing it to actuate theelectromechanical device. A message will be sent to the surface from theelectronics control module 50 indicating that the command was executed.Alternatively, the downhole electronics module may automatically actuatethe electromechanical device without an external command from thesurface.

8. The operator can inquire the status of wells from a remote location10 by establishing a phone or satellite link to the desired location.The remote surface computer 24 will ask the operator for a password forproper access to the remote system.

9. A message will be sent from the downhole module 22 in the well to thesurface system 24 indicating that an electromechanical device 64 wasactuated by the downhole electronics 50 if a flow or borehole parameterchanged outside the normal operating range. The operator will have theoption to question the downhole module as to why the action was taken inthe borehole and overwrite the action by commanding the downhole moduleto go back to the original status. The operator may optionally send tothe module a new set of parameters that will reflect the new operatingranges.

10. During an emergency situation or loss of power all devices willrevert to a known fail safe mode.

The production well control system of this invention may utilize a widevariety of conventional as well as novel downhole tools, sensors,valving and the like. Examples of certain preferred and novel downholetools for use in the system of the present invention include:

1. a retrievable sensor gauge side pocket mandrel;

2. subsurface safety valve position and pressure monitoring system;

3. remotely controlled inflation/deflation device with pressuremonitoring;

4. remotely actuated downhole tool stop system;

5. remotely controlled fluid/gas control system; and

6. remotely controlled variable choke and shut-off valve system.

The foregoing listed tools will now be described with reference to FIGS.8-13.

Retrievable Pressure Gauge Side Pocket Mandrel with Inductive Coupler

Traditional permanent downhole gauge (e.g. sensor) installations requirethe mounting and installation of a pressure gauge external to theproduction tubing thus making the gauge an integral part of the tubingstring. This is done so that tubing and/or annulus pressure can bemonitored without restricting the flow diameter of the tubing. However,a drawback to this conventional gauge design is that should a gauge failor drift out of calibration requiring replacement, the entire tubingstring must be pulled to retrieve and replace the gauge. In accordancewith the present invention an improved gauge or sensor construction(relative to the prior art permanent gauge installations), is to mountthe gauge or sensor in such a manner that it can be retrieved by commonwireline practices through the production tubing without restricting theflow path. This is accomplished by mounting the gauge in a side pocketmandrel.

Side pocket mandrels have been used for many years in the oil industryto provide a convenient means of retrieving or changing out servicedevices needed to be in close proximity to the bottom of the well orlocated at a particular depth. Side pocket mandrels perform a variety offunctions, the most common of which is allowing gas from the annulus tocommunicate with oil in the production tubing to lighten it for enhancedproduction. Another popular application for side pocket mandrels is thechemical injection valve, which allows chemicals pumped from thesurface, to be introduced at strategic depths to mix with the producedfluids or gas. These chemicals inhibit corrosion, particle build up onthe I.D. of the tubing and many other functions.

As mentioned above, permanently mounted pressure gauges havetraditionally been mounted to the tubing which in effect makes them partof the tubing. By utilizing a side pocket mandrel however, a pressuregauge or other sensor may be installed in the pocket making it possibleto retrieve when necessary. This novel mounting method for a pressuregauge or other downhole sensor is shown in FIGS. 8 and 8A. In FIG. 8, aside pocket mandrel (similar to side pocket mandrel 282 in FIG. 14) isshown at 86 and includes a primary through bore 88 and a laterallydisplaced side pocket 90. Mandrel 86 is threadably connected to theproduction tubing using threaded connection 92. Positioned in sidepocket 90 is a sensor 94 which may comprise any suitable transducer formeasuring flow, pressure, temperature or the like. In the FIG. 8embodiment, a pressure/temperature transducer 94 (Model 2225A or 2250Acommercially available from Panex Corporation of Houston, Tex.) isdepicted having been inserted into side pocket 90 through an opening 96in the upper surface (e.g., shoulder) 97 of side pocket 90 (see FIG.8A).

Information derived from downhole sensor 94 may be transmitted to adownhole electronic module 22 as discussed in detail above or may betransmitted (through wireless or hardwired means) directly to a surfacesystem 24. In the FIGS. 8 and 8A embodiments, a hardwired cable 98 isused for transmission. Preferably the cable 98 comprises tubular encasedconductor or TEC available from Baker Oil Tools of Houston, Tex. TECcomprises a centralized conductor or conductors encapsulated in astainless steel or other steel jacket with or without epoxy filling. Anoil or other pneumatic or hydraulic fluid fills the annular area betweenthe steel jacket and the central conductor or conductors. Thus, ahydraulic or pneumatic control line is obtained which contains anelectrical conductor. The control line can be used to convey pneumaticpressure or fluid pressure over long distances with the electricalinsulated wire or wires utilized to convey an electrical signal (powerand/or data) to or from an instrument, pressure reading device, switchcontact, motor or other electrical device. Alternatively, the cable maybe comprised of Center-Y tubing encased conductor wire which is alsoavailable from Baker Oil Tools. This latter cable comprises one or morecentralized conductor encased in a Y-shaped insulation, all of which isfurther encased in an epoxy filled steel jacket. It will be appreciatedthat the TEC cable must be connected to a pressure sealed penetratingdevice to make signal transfer with gauge 94. Various methods includingmechanical (e.g., conductive), capacitive, inductive or optical methodsare available to accomplish this coupling of gauge 94 and cable 92. Apreferred method which is believed most reliable and most likely tosurvive the harsh downhole environment is a known "inductive coupler"99.

Transmission of electronic signals by means of induction have been inuse for many years most commonly by transformers. Transformers are alsoreferred to as inductors, provide a means of transmitting electricalcurrent without a physical connection by the terminal devices.Sufficient electrical current flowing through a coil of wire can inducea like current in a second coil if it is in very close proximity to thefirst. The drawback of this type of transmission is that efficiency islow. A loss of power is experienced because there is no physical contactof conductors; only the influence of one magnetic field in the sourcecoil driving an electric current in the second. To achieve communicationthrough the inductive device 99, an alternating current (AC) must beused to create the operating voltage. The AC is then rectified orchanged to direct current (DC) to power the electronic components.

Much like the inductive coupler or transformer method of signaltransmission, a very similar principle exists for what are known as"capacitive couplers". These capacitance devices utilize the axiom thatwhen two conductors or poles in close proximity to each other arecharged with voltages or potential differences of opposite polarity, acurrent can be made to flow through the circuit by influencing one ofthe poles to become more positive or more negative with respect to theother pole. When the process is repeated several times a second, afrequency is established. When the frequency is high enough, (severalthousand times per second), a voltage is generated "across" the twopoles. Sufficient voltage can be created to provide enough power formicroprocessing and digital circuitry in the downhole instruments. Oncepowered up, the downhole device can transmit; radio-metric, digital ortime shared frequency trains which can be modulated on the generatedvoltage and interpreted by the surface readout device. Thus, acommunication is established between downhole device and the surface. Aswith inductive devices, capacitive devices can suffer line loss throughlong lengths of cable if the communication frequency is too high causingthe signal to be attenuated by the inherent capacitance of the cableitself. Again, as with the inductive devices, capacitive devices mustuse the alternating current (AC) method of transmission withrectification to DC to power the electronics.

By transmitting beams of light through a glass fiber cable, electronicdevices can also communicate with one another using a light beam as aconductor as opposed to a solid metal conductor in conventional cable.Data transmission is accomplished by pulsing the light beam at thesource (surface instrument which is received by an end device (downholeinstrument) which translates the pulses and converts them intoelectronic signals.

Conductive or mechanical coupling is simply making a direct physicalconnection of one conductor to another. In the side pocket mandrel 86, aconductor is present in the pocket 90, pressure sealed as it penetratesthe body of the side pocket and mated to an external device to transmitthe signal to the surface (i.e., solid conductor cable, wirelesstransceiver or other device). The hard wired coupler may exist in anyform conducive to proper electronic signal transmission while notcompromising the pressure sealing integrity of the tool. The couplermust also be capable of surviving exposure to harsh downhole conditionswhile in the unmated condition as would be the case when an instrument94 was not installed in the pocket 90.

The preferred inductive coupler 99 is connected to TEC cable 98 using apressure sealed connector 95.

With the gauge or other sensor 90 being internal and exposed to the I.D.of the tubing 88, and the cable 98 being external to the mandrel 86, butexposed to the annulus environment, the connector 95 must penetrate themandrel pocket 90 allowing gauge 94 and cable 98 to be mated. Due topressure differences between the tubing I.D. and the annulus, connector95 also provides a pressure seal so as to prevent communication betweenthe mandrel and annulus.

An electronic monitoring device 94 which is "landed" in side pocket 90of mandrel 86, includes a latching mechanism 101 to keep sensor 94 inplace as pressure is exerted on it either from the interior of themandrel or the annulus side. This latching mechanism 101 also provides ameans of being unlatched so the device may be retrieved. Several methodsexist to accomplish this latching, such as using specific profiles inpocket 90 that align with spring loaded dogs (not shown) on the sensordevice 94. Once aligned, the springs force the locking dogs out to meetthe profile of the pocket 90 providing a lock, much like tumblers in anordinary household key operated lock. This locking action prevents thesensor tool 94 from being dislodged from its landing seat. This isimportant as any movement up or down could cause misalignment and impairthe integrity of the electronic coupling device 99 to which the sensortool 94 is now mated.

The latching mechanism 101 must be of sufficient robustness as to beable to withstand several landing and retrieval operations withoutcompromising the integrity of the latching and release properties ofsensor tool 94.

As mentioned, pressure integrity should be maintained to keep themandrel isolated from the annulus. When the sensor tool 94 is beinglanded in pocket 90, it should activate or deactivate pressure sealingdevice 95 to expose the sensing portion of the sensor tool 94, to eitherthe mandrel or annulus. Similarly, when sensor tool 94 is retrieved frompocket 90, it must also seal off any pressure port that was openedduring the landing procedure.

The pressure porting mechanism is capable of being selectively opened toeither the annulus or the mandrel. The selection device can be, but isnot limited to, a specific profile machined to the outer housing of thesensor tool 94 combined with different configurations oflocking/actuating dogs to: open a sliding sleeve, sting into a dedicatedpressure port, displace a piston or any suitable configuration ofpressure port opening or closing devices. Once activating the selectedport, a positive seal must be maintained on the unselected port toprevent leakage or sensing of an undesired condition (pressure, flow,water cut etc.) while in the unmated condition as would be the case whenan instrument was not installed in the pocket.

Subsurface Safety Valve Position and Pressure Monitoring System

Referring to FIG. 9, a subsurface safety valve position and pressuremonitoring system is shown generally at 100. System 100 includes a valvehousing 102 which houses a downhole valve such as a shut-in valve 104.Various pressure and positioning parameters of shut-in valve 104 aredetermined through the interaction of five sensors which are preferablytied to a single electrical single conductor or multi conductor line(e.g., the aforementioned TEC cable). These five sensors remotelymonitor the critical pressures and valve positions relative to safe,reliable remotely controlled subsurface safety valve operations. Thedownhole sensors include four pressure sensors 106, 108, 110 and 112 andone proximity sensor 114. Pressure sensor or transducer 106 ispositioned to sense tubing pressure upstream of shut-in valve 104.Pressure transducer 108 is positioned to sense the hydrauliccontrol-line pressure from hydraulic control-line 116. Pressuretransducer 110 is positioned to sense the annulus pressure at a givendepth while pressure transducer 112 is positioned to sense the tubingpressure downstream of valve 104. Proximity sensor 114 is positionedexternal to the valve or closure member 104 and functions so as toenable confirmation of the position of the valve 104. Encoded signalsfrom each of the sensors 106 through 114 are fed back to the surfacesystem 24 or to a downhole module 22 through a power supply/data cable118 connected to the surface system 24 or downhole module 22.Alternatively, the encoded signals may be transmitted by a wirelesstransmission mechanism. Preferably cable 118 comprises tubingencapsulated single or multiconductor line (e.g., the aforementioned TECcable) which is run external to the tubing stream downhole and serves asa data path between the sensors and the surface control system.

A downhole module 22 may automatically or upon control signals sent fromthe surface, actuate a downhole control device to open or shut valve 104based on input from the downhole sensors 106 through 114.

The foregoing subsurface valve position and pressure monitoring systemprovides many features and advantages relative to prior art devices. Forexample, the present invention provides a means for absolute remoteconfirmation of valve position downhole. This is crucial for confidentthrough tubing operations with wireline or other conveyance means and isalso crucial for accurate diagnosis of any valve system malfunctions. Inaddition, the use of the subsurface safety valve position and pressuremonitoring system of this invention provides real time surfaceconfirmation of proper pressure conditions for fail-safe operation inall modes. Also, this system provides a means for determination ofchanges in downhole conditions which could render the safety systeminoperative under adverse or disaster conditions and the presentinvention provides a means for surface confirmation of proper valveequalization prior to reopening after downhole valve closure.

Remotely Controlled Inflation/Deflation Device with a PressureMonitoring System

Referring now to FIG. 10, a microprocessor based device for monitoringof pressures associated with the inflation of downhole tools ispresented. This microprocessor based device can be actuated eitherautomatically by the downhole control module 22 or the downhole controlmodule 22 may actuate the present device via a surface signal which istransmitted downhole from the surface system 24. In FIG. 10, theinflatable element (such as a packer) is shown at 124 and is mounted ina suitable mandrel 126. Associated with inflatable element 124 is avalve housing 128 which includes an axial opening 130 having a firstdiameter and a coaxial cavity 132 having a second diameter larger thanthe first diameter. Also within valve housing 128 is a motor 134 whichactuates appropriate gearing 136 so as to provide linear translation toa shaft 138 having a piston-type valve 140 mounted to one end thereof.As shown by the arrows in FIG. 10, motor 130 actuates gearing 136 so asto move piston 140 between a closed or shut-off position in which piston140 resides completely in axial opening 130 and an open position whereinpiston 140 resides within the central cavity 132. Axial opening 130terminates in the interior of valve housing 128 at an inflation port 142through which fluid from an inflation fluid source 144 enters and exitsin the interior of valve housing 128.

In accordance with an important feature of the present invention, theinflation/deflation device 124 is remotely controlled and/or monitoredusing a plurality of sensors in conjunction with a microprocessor basedcontroller 146. Of course controller 146 is analogous to the downholemodules 22 discussed in great detail above in connection with forexample, FIGS. 6 and 7. In a preferred embodiment of this invention, apair of pressure transducers communicate with microprocessor controller146. One pressure transducer is shown at 148 and resides within theinternal cavity 132 of valve housing 128. The second pressure transduceris shown at 150 and resides in the inflation port 142. In addition, apair of cooperating proximity sensors 152 and 154 are positioned betweenvalve housing 128 and the mandrel 126. Preferably, both power and dataare supplied to controller 146 through appropriate cable 156 via apressure fitting 158. This cable is preferably the TEC cable describedabove. Power may also be supplied by batteries or the like and data maybe transmitted using wireless methods.

It will be appreciated that the sealing device of this inventionfunctions as a valve and serves to positively open and close theinflation fluid passage thereby permitting movement of inflation fluidfrom the fluid source 144 to the sealing element 124. In the particularembodiment described in FIG. 10, the valve 140 operates by axiallydisplacing the sealing element 124 between the two diametrical boreswithin the fluid passageway by way of the motor gearing mechanism134/136 all of which is driven by the on-board microprocessor 146. Valve140 has two functional positions i.e., open and closed. Of course, thevalve could function in alternative manners such as a solenoid. Theelectronic controller 146 serves to integrate the pressure inputs frompressure transducers 148 and 150 and the proximity inputs from proximitysensors 152 and 154 along with the data/control path 156 toappropriately drive the control valve mechanism during tool inflation.Thereafter, the sensors 148, 150, 152 and 154 serve to ensure pressureintegrity and other tool position functions.

The remotely controlled inflation/deflation device of the presentinvention offers many features and advantages. For example, the presentinvention eliminates the present standard industry design for pressureactuated shear mechanisms which are subject to wide variations inactuation pressures and premature inflation. The present inventionprovides a directly controllable mechanism for initiation of downholetool inflation and through the unique self cleaning inflation controlvalve configuration shown in FIG. 10, obsoletes present designconfigurations which are subject to fouling by debris in the inflationfluid. In addition, the present invention enables direct control ofclosure of the inflation valve whereas in the prior art, spring loadedand pressure actuated designs resulted in pressure loss during operationand unreliable positive sealing action. The use of a motor driven,mechanical inflation control valve also constitutes an important featureof this invention. Still another feature of this invention is theincorporation of electronic proximity sensors in relation to inflatabletools so as to ensure correct positioning of selective inflation tools.High angle/horizontal orientation of inflatable tools requiresconveyance of inflation tools via coil tubing which is subject tosubstantial drag. In contrast to the present invention, the prior arthas been limited to positioning of inflation tools by collet typedevices or pressure operated devices, both of which were highlyunreliable under these conditions. The use of a microprocessor inconjunction with an inflatable downhole tool and the use of amicroprocessor based system to provide both inflation and deflation tocontrol the downhole tools also constitute important features of thisinvention. The present invention thus enables multiple, resettableoperations in the event that procedures may so require or in the eventof initially incorrect positioning of tools within a wellbore. Finally,the present invention provides a continuous electronic pressuremonitoring system to provide positive, real time wellbore and/zonalisolation integrity downhole.

Remotely Actuated Downhole Tool Stop System

Referring to FIGS. 11A and 11B, a remotely actuated tool stop inaccordance with the present invention is shown generally at 160. In theembodiment shown, the remotely actuated tool stop includes a side pocketmandrel 162 having a primary bore 164 and a side bore 166. A tool stop168 is pivotally mounted onto a threaded shaft 170 with shaft 170 beingsealed by seal 172 to prevent the flow of fluid or other debris intosidebore 166. Threaded shaft 170 is connected to a holddown 174 which inturn is connected to appropriate gearing 176 and a motor 178. Whilemotor 178 may be powered by a variety of known means, preferably aninductive coupler 180 of the type described above is used to power themotor through a tubular encased conductor or TEC 192 as described above.Note that a pressure relief port 184 is provided between sidebore 166and primary bore 164.

The foregoing system described in FIG. 11A functions to provide aremotely actuated device which positively limits the downward movementof any tools used within the wellbore. A primary utilization of the toolstop includes use as a positioning device at close proximity (i.e.below) to a tool, for example or the side pocket mandrel 162. The systemof this invention may also be used with other difficult to locatedevices in high angle or horizontal wellbores. In this manner, whenactivated as shown in FIG. 11A, the surface operator may proceeddownward with a work string until contact is made with tool stop 168.The tools and/or work string being delivered downhole may then be pulledback up a known distance thus ensuring proper positioning to perform theintended function in the targeted receptacle. An alternative functionwould be as a general purpose safety device, positioned close to thebottom of the tubing string in the wellbore. The tool stop system ofthis invention would then be activated whenever wireline or coiledtubing operations are being performed above and within the wellbore. Inthe event that the work string or individual tools are accidentallydropped, the tool stop of this invention ensures that they are not lostdownhole and provides for easy retrieval at the tool stop depth. Afterthrough tubing operations are concluded, the tool stop system of thisinvention is deactivated/retracted as shown in FIG. 11B to provide aclear tubing bore 164 for normal well production or injection. It willbe appreciated that during use, motor 178 will actuate gearing 176 whichin turn will rotate threaded shall 170 so as to raise tool stop 168 tothe position shown in FIG. 11A or lower (deactivate or withdraw) toolstop 168 to the retracted position shown in FIG. 11B. The motor will bedigitally controlled by an electronics control module 22 provided ininductive coupler section 180. Control module 22 can either be actuatedby a surface or external control signal or may be automatically actuateddownhole based on preprogrammed instructions as described above withregard to FIG. 7.

The remotely actuated tool stop of the present invention offers manyfeatures and advantages including a means for selective surfaceactuation of a downhole device to prevent tool loss; a means forselective surface actuation of a downhole device to provide for positivetool location downhole and as a means to prevent accidental impactdamage to sensitive tools downhole such as subsurface safety valves andinflatable tubing plugs.

Remotely Controlled Fluids/Gas Control System

Referring now to FIG. 12, a remotely controlled fluid/gas control systemis shown and includes a side pocket mandrel 190 having a primary bore192 and a side bore 194. Located within side bore 194 is a removableflow control assembly in accordance with the present invention. Thisflow control assembly includes a locking device 196 which is attached toa telescopic section 198 followed by a gas regulator section 200, afluid regulator section 202, a gear section 204 and motor 206.Associated with motor 206 is an electronics control module 208. Threespaced seal sections 210, 212 and 214 retain the flow control assemblywithin the side bore or side pocket 194. Upon actuation by electronicsmodule 208, control signals are sent to motor 206 which in turn actuategears 204 and move gas regulator section 200 and fluid regulator section202 in a linear manner upwardly or downwardly within the side pocket194. This linear movement will position either the gas regulator section200 or the fluid regulator section 202 on either side of an inlet port216.

Preferably, electronics control module 208 is powered and/or datasignals are sent thereto via an inductive coupler 218 which is connectedvia a suitable electrical pressure fitting 220 to the TEC cable 192 ofthe type discussed above. A pressure transducer 224 senses pressure inthe side pocket 194 and communicates the sensed pressure to theelectronics control module 208 (which is analogous to downhole module22). A pressure relief port is provided to side pocket 194 in the areasurrounding electronics module 208.

The flow control assembly shown in FIG. 12 provides for regulation ofliquid and/or gas flow from the wellbore to the tubing/casing annulus orvice versa. Flow control is exercised by separate fluid and gas flowregulator subsystems within the device. Encoded data/control signals aresupplied either externally from the surface or subsurface via a datacontrol path 222 and/or internally via the interaction of the pressuresensors 224 (which are located either upstream or downstream in thetubing conduit and in the annulus) and/or other appropriate sensorstogether with the on-board microprocessor 208 in a manner discussedabove with regard to FIGS. 6 and 7.

The flow control assembly of this invention provides for two unique anddistinct subsystems, a respective fluid and gas flow stream regulation.These subsystems are pressure/fluid isolated and are contained with theflow control assembly. Each of the systems is constructed for thespecific respective requirements of flow control and resistance todamage, both of which are uniquely different to the two control mediums.Axial reciprocation of the two subsystems, by means of the motor 206 andgear assembly 204 as well as the telescopic section 198 permitspositioning of the appropriate fluid or gas flow subsystem inconjunction with the single fluid/gas passages into and out of the sidepocket mandrel 190 which serves as the mounting/control platform for thevalve system downhole. Both the fluid and gas flow subsystems allow forfixed or adjustable flow rate mechanisms.

The external sensing and control signal inputs are supplied in apreferred embodiment via the encapsulated, insulated single ormulticonductor wire 222 which is electrically connected to the inductivecoupler system 218 (or alternatively to a mechanical, capacitive oroptical connector), the two halves of which are mounted in the lowerportion of the side pocket 194 of mandrel 190, and the lower portion ofa regulating valve assembly respectively. Internal inputs are suppliedfrom the side pocket 194 and/or the flow control assembly. All signalinputs (both external and internal) are supplied to the on-boardcomputerized controller 208 for all processing and distributive control.In addition to processing of offboards inputs, an ability for on-boardstorage and manipulation of encoded electronic operational "models"constitutes one application of the present invention providing forautonomous optimization of many parameters, including supply gasutilization, fluid production, annulus to tubing flow and the like.

The remotely controlled fluid/gas control system of this inventioneliminates known prior art designs for gas lift valves which forcesfluid flow through gas regulator systems. This results in prolonged lifeand eliminates premature failure due to fluid flow off the gasregulation system. Still another feature of this invention is theability to provide separately adjustable flow rate control of both gasand liquid in the single valve. Also, remote actuation, control and/oradjustment of downhole flow regulator is provided by this invention.Still another feature of this invention is the selected implementationof two devices within one side pocket mandrel by axialmanipulation/displacement as described above. Still another feature ofthis invention is the use of a motor driven, inductively coupled devicein a side pocket. The device of this invention reduces total quantity ofcirculating devices in a gas lift well by prolonging circulatingmechanism life. As mentioned, an important feature of this invention isthe use of a microprocessor 208 in conjunction with a downhole gaslift/regulation device as well as the use of a microprocessor inconjunction with a downhole liquid flow control device.

Remotely Controlled Variable Choke and Shut-Off Valve System

Referring to FIG. 13, a remotely controlled downhole device is shownwhich provides for actuation of a variable downhole choke and positivelyseals off the wellbore above from downhole well pressure. This variablechoke and shut-off valve system is subject to actuation from thesurface, autonomously or interactively with other intelligent downholetools in response to changing downhole conditions without the need forphysical reentry of the wellbore to position a choke. This system mayalso be automatically controlled downhole as discussed with regard toFIGS. 6 and 7. As will be discussed hereinafter, this system containspressure sensors upstream and downstream of the choke/valve members andreal time monitoring of the response of the well allows for a continuousadjustment of choke combination to achieve the desired wellbore pressureparameters. The choke body members are actuated selectively andsequentially, thus providing for wireline replacement of choke orificesif necessary.

Turning to FIG. 13, the variable choke and shut off valve system of thisinvention includes a housing 230 having an axial opening 232therethrough. Within axial opening 232 are a series (in this case two)of ball valve chokes 234 and 236 which are capable of being actuated toprovide sequentially smaller apertures; for example, the aperture inball valve choke 234 is smaller than the relatively larger aperture inball valve choke 236. A shut-off valve 238, may be completely shut offto provide a full bore flow position through axial opening 232. Eachball valve choke 234 and 236 and shut-off valve 238 are releasablyengageable to an engaging gear 240, 242 and 244, respectively. Theseengaging gears are attached to a threaded drive shaft 246 and driveshaft 246 is attached to appropriate motor gearing 248 which in turn isattached to stepper motor 250. A computerized electronic controller 252provides actuation control signals to stepper motor 250. Downholecontroller 252 communicates with a pair of pressure transducers, onetransducer 254 being located upstream of the ball valve chokes and asecond pressure transducer 256 being located downstream of the ballvalve chokes. Microprocessor controller 252 can communicate with thesurface either by wireless means of the type described in detail aboveor, as shown in FIG. 13 by hard wired means such as the power/datasupply cable 258 which is preferably of the TEC type described above.

As shown in FIG. 13, the ball valve chokes are positioned in a stackedconfiguration within the system and are sequentially actuated by thecontrol rotation mechanism of the stepper motor, motor gearing andthreaded drive shaft. Each ball valve choke is configured to have twofunctional positions: an "open" position with a fully open bore and an"actuated" position where the choke bore or closure valve is introducedinto the wellbore axis. Each member rotates 90° pivoting about itsrespective central axis into each of the two functional positions.Rotation of each of the members is accomplished by actuation of thestepper motor which actuates the motor gearing which in turn drives thethreaded drive shaft 246 such that the engaging gears 240, 242 or 244will engage a respective ball valve choke 234 or 236 or shut-off valve238. Actuation by the electronic controller 252 may be based, in partupon readings from pressure transducers 254 and 256 or by a controlsignal from the surface.

The variable choke and shut-off valve system of the present inventionprovides important features and advantages including a novel means forthe selective actuation of a downhole adjustable choke as well as anovel means for installation of multiple, remotely or interactivelycontrolled downhole chokes and shut-off valves to providetuned/optimized wellbore performance.

While preferred embodiments have been shown and described, modificationsand substitutions may be made thereto without departing from the spiritand scope of the invention. Accordingly, it is to be understood that thepresent invention has been described by way of illustrations and notlimitation.

What is claimed is:
 1. A system for the downhole control and monitoringof fluid produced in a production well, said well including at least afirst and second zone for producing fluid, comprising:at least onedownhole fluid flow control tool disposed downhole in the each of saidfirst and second zones of said well; and a downhole control andmonitoring system permanently disposed downhole in each of said firstand second zones of said well for controlling production of fluidflowing from the formation into the production well and then to thesurface of the production well, said downhole control and monitoringsystem including;at least one downhole sensor for sensing a downholeparameter; at least one downhole control device for controlling said atleast one downhole flow control tool; and a downhole electroniccontroller in communication with said downhole sensor and said downholecontrol device, said downhole electronic controller automaticallycontrolling said downhole fluid flow control tool in response to inputfrom said downhole sensor.
 2. The system of claim 1 wherein each of saiddownhole electronic controllers includes:a memory for storing a set ofinstructions; and a processor connected to said memory for executingsaid set of instructions in response to said input from said downholesensor.
 3. The system of claim 2 wherein:said set of instructionsincludes a selected operating range for a selected downhole parametersensed by said downhole sensor and wherein said downhole electroniccontroller controls said downhole control device when said selecteddownhole parameter sensed by said downhole sensor is outside saidselected operating range.
 4. The system of claim 3 wherein:said selectedoperating range is preprogrammed into said memory prior to disposingsaid downhole electronic controller downhole.
 5. The system of claim 3wherein:said selected operating range is programmed into said memorywhile said downhole electronic controller is downhole using externalsignals sent from the surface.
 6. The system of claim 1 wherein: each ofsaid downhole control devices comprise an electromechanical device. 7.The system of claim 6 wherein:said electromechanical control devicechanges the state of said downhole fluid flow control tool in responseto input from said downhole electronic controller.
 8. The system ofclaim 1 wherein:each of said downhole tools are selected from the groupconsisting of sliding sleeves, pumps and valves.
 9. The system of claim1 wherein:at least one of said downhole sensors comprise a formationevaluation sensor.
 10. The system of claim 9 wherein:said formationevaluation sensor is selected from the group consisting of nuclear,gamma ray, electromagnetics and acoustical sensors.
 11. The system ofclaim 9 wherein:said formation evaluation sensor measures at least oneof formation geology, formation saturation, formation porosity,formation chemical elements, gas influx, water content and petroleumcontent.
 12. The system of claim 1 wherein:at least one of said downholesensors comprise a sensor for measuring parameters within a borehole ofthe well.
 13. The system of claim 12 wherein:said downhole sensorcomprises at least one sensor for measuring temperature, pressure, flowand oil/water ratio.
 14. The system of claim 1 wherein:said downholesensors include at least one formation evaluation sensor and at leastone flow sensor.
 15. The system of claim 1 including:a downhole powersource for providing electrical power to each of said downholeelectronic controllers.
 16. The system of claim 15 wherein:said downholepower source is selected from the group consisting of batteries andturbines.
 17. The system of claim 1 including:a downhole receiver incommunication with at least one of said downhole electronic controllers,said downhole receiver adapted for receiving at least one of data andcontrol signals from the surface.
 18. The system of claim 1 including:adownhole transmitter in communication with at least one of said downholeelectronic controllers, said downhole transmitter adapted fortransmitting signals from said downhole electronic controller to thesurface or to another location downhole.
 19. The system of claim 1wherein:each of said downhole electronic controllers comprise a dataacquisition system in communication with a processor.
 20. The system ofclaim 1 wherein at least one of said first and second zones includes:aplurality of downhole control devices for controlling a plurality ofdownhole fluid flow control tools.
 21. The system of claim 1 including:asurface system located on the surface of the well for monitoringinformation acquired downhole.
 22. The system of claim 21 wherein saidsurface system comprises:a computer for processing information acquireddownhole and for interfacing with an operator; a transmittercommunicating with said computer for sending information downhole to atleast one of said downhole control and monitoring systems; and areceiver communicating with said computer for receiving informationtransmitted from at least one of said downhole control and monitoringsystems.
 23. The system of claim 21 including:a telemetry devicecommunicating with said surface system for transmitting informationacquired downhole to a remote location.
 24. The system of claim 1wherein:said well includes a primary borehole and at least one branchborehole extending from said primary borehole, said first zone residingin said primary borehole and said second zone residing is said branchborehole.
 25. The system of claim 1 wherein:said well includes a primaryborehole and at least first and second branch boreholes extending fromsaid primary borehole, said first zone residing in said first branchborehole and said second zone residing in said second branch borehole.26. The system of claim 1 wherein:said downhole electronic controller insaid first zone is adapted to communicate with said downhole electroniccontroller in said second zone.
 27. The system of claim 1 wherein:saidautomatic control is initiated by said downhole electronic controllerswithout an external signal or stimulus from the surface.
 28. The systemof claim 1 wherein:each of said downhole fluid flow control tools iscontrolled by respective ones of said downhole electronic controllersusing control signals originating at least in part from downhole. 29.The system of claim 1 wherein:each of said downhole fluid flow controltools is controlled by respective ones of said downhole electroniccontrollers using control signals originating downhole.
 30. The systemof claim 1 including:a single cable from the surface to said downholeelectronic controller for supplying both power and data or controlsignals.
 31. The system of claim 1 wherein:each of said downholeelectronic controllers processes raw data sensed by said downhole sensorto derive processed data, said processed data being used for at leastone of controlling production of said well and for transmission to thewell surface.
 32. A method for controlling fluid produced from at leasttwo first and second production zones in a production wellcomprising:sensing in said first and second production zones at leastone downhole parameter to define at least one sensed parameter; and ineach of said first and second production zones, automaticallycontrolling at least one downhole fluid flow control tool in response tothe sensed parameter utilizing a downhole computerized control systemwhich has been permanently deployed downhole to control production offluid flowing from the formation into the production well and then tothe surface of the production well.
 33. The method of claim 32wherein:said automatic control of said downhole fluid flow control toolsoccur when said downhole parameters are outside a selected range. 34.The method of claim 32 including:preprogramming said selected range atthe surface.
 35. The method of claim 32 wherein:said downhole fluid flowcontrol tools are selected from the group consisting of sliding sleeves,pumps and valves.
 36. The method of claim 32 including:transmitting atleast one of data or control signals from downhole to the surface or toanother location downhole.
 37. The method of claim 32including:initiating said automatic control without an external stimulusor signal from the surface.
 38. The method of claim 32including:initiating said automatic control using signals originating,at least in part from downhole.
 39. The method of claim 32 wherein:saiddownhole computerized control system processes raw data based on thesensed parameters to derive processed data, said processed data beingused for at least one of controlling production of said well and fortransmission to the well surface.